Untangling surface oxygen exchange effects in YBa2Cu3O6+x thin films by electrical conductivity relaxation

The kinetics of oxygen incorporation (in-diffusion process) and excorporation (out-diffusion process), in YBa₂Cu₃O_6+x (YBCO) epitaxial thin films prepared using the chemical solution deposition (CSD) methodology by the trifluoroacetate route, was investigated by electrical conductivity relaxation measurements. We show that the oxygenation kinetics of YBCO films is limited by the surface exchange process of oxygen molecules prior to bulk diffusion into the films. The analysis of the temperature and oxygen partial pressure influence on the oxygenation kinetics has drawn a consistent picture of the oxygen surface exchange process enabling us to define the most likely rate determining step. We have also established a strategy to accelerate the oxygenation kinetics at low temperatures based on the catalytic influence of Ag coatings thus allowing us to decrease the oxygenation temperature in the YBCO thin films.

Prevalence of myasthenia gravis in the Catalan county of Osona

INTRODUCTION

The reported prevalence of myasthenia gravis ranges between 5 and 24 cases per 100,000, and people over 65years account for less than 50% of all cases. The prevalence and clinical characteristics of myasthenia gravis in the county of Osona were studied in patients younger and older than 65.

METHODS

The study draws from the county-based prospective myasthenia gravis register implemented by the Neurology Department at Hospital General de Vic in 1991.

RESULTS

The prevalence of myasthenia gravis was 32.89×10⁵ inhabitants (95%CI, 23.86-41.91). The standardized prevalence (European population) was 35.47×10⁵ inhabitants (95%CI, 26.10-44.84). The ratio of women to men was 1.3. Overall, the group of patients older than 65 accounted for 62.75% of all cases. The prevalence of myasthenia gravis increased considerably in older age groups. No cases were registered among patients under 25years old, prevalence was 21.87×10⁵ in the 25 to 64 age group, and prevalence in patients over 65 years increased to 122.35×10⁵. The clinical characteristics prior to treatment and at the cut-off date are similar (P>.05) in patients younger than 65 and those aged 65 and older.

CONCLUSIONS

These figures show the highest prevalence rate reported to date. This high prevalence is due to the rate observed among patients older than 65. These results provide a new warning that myasthenia gravis may be underdiagnosed in the elderly population.

Knowledge, attitude and adherence of Spanish healthcare professionals to asthma management recommendations during pregnancy

BACKGROUND

The aim of the present study was to evaluate the knowledge, attitude and adherence to asthma management recommendations during pregnancy of Spanish health care professionals.

METHODS

A multiple choice survey with 14 questions was designed. Items assessed opinion about asthma guidelines and attitudes towards treatment, spirometry, specific immunotherapy and labour in pregnant asthmatic patients. Test completion was voluntary, individual, and anonymous.

RESULTS

A total of 1000 questionnaires were fulfilled: respiratory medicine specialists (19.8%); allergy specialists (17.2%); primary care physicians (46.1%); and gynaecologists/obstetricians (16.9%). Guidelines were considered useful by 96.5% although 64% admitted that they followed them seldom or never. Most physicians (55.9%) answered that they would maintain asthma therapy in clinically stable patients. Almost 30% of physicians would not perform spirometry in pregnant asthma patients. 19% declared they would interrupt specific immunotherapy which had proven safe and effective. Univariate analysis revealed low adherence to be associated with the following variables: age, primary care or gynaecology/obstetrician specialisation, number of asthmatics attended per month, and declared use of guidelines for pregnant asthmatic patients. Multivariate analysis showed that being a primary care physician and a gynaecologist/obstetrician, attending a low number of asthma patients per month, and poor use of spirometry during pregnancy are associated to low adherence to asthma guidelines.

CONCLUSION

Even though the majority of Spanish physicians surveyed seem to consider guidelines useful, their adherence to those is very low if translated to managing pregnant asthmatic patients. Educational strategies seem unavoidable and should be targetted mainly to primary care and gynaecology/obstetrician physicians.

Growth of epitaxial CeO2 buffer layers by polymer assisted deposition

Polymer assisted deposition (PAD) has been reported as a novel CSD approach for thin film growth with improved homogeneity and long stability by forming a metal polymer species. It also offers the interesting possibility of having a library of PAD solutions for each precursor metal and obtaining the required composition by simple mixing. Another potential advantage is the increase in thickness since mechanical stresses are expected to be alleviated during shrinkage in the metalorganic decomposition by the metal-polymer network.

Cerium oxide films on YSZ single crystals were grown from water-based solutions containing cerium nitrate, polyethyleneimine and complexing EDTA, in order to explore the benefits of using the PAD approach for growing buffer layers in coated conductors. An ultrafiltration step was performed to remove the non-coordinated species in solution. The degree of purification and efficiency in the cerium recovery was investigated by different techniques. TGA-DTA analysis was used to provide guidance to the best thermal profiles in different atmospheres and specially to diminish the adverse effects of exothermic events during decomposition. Microstructural evolution was tracked by AFM and TEM, while epitaxial fraction was followed by X-ray diffraction. The results show the high importance of choosing the proper atmosphere and the need for tuning of heating ramps to obtain dense, flat and epitaxial ceria films by PAD.

Can the crystallization rate be independent from the crystallization enthalpy? The case of amorphous silicon

The crystallization enthalpy measured in a large series of amorphous silicon (a-Si) materials varies within a factor of 2 from sample to sample (Kail et al 2011 Phys. Status Solidi RRL 5 361). According to the classical theory of nucleation, this variation should produce large differences in the crystallization kinetics leading to crystallization temperatures and activation energies exceeding 550 °C and 1.7 eV, respectively, the 'standard' values measured for a-Si obtained by self-implantation. In contrast, the observed crystallization kinetics is very similar for all the samples studied and has no correlation with the crystallization enthalpy. This discrepancy has led us to propose that crystallization in a-Si begins in microscopic domains that are almost identical in all samples, independently of their crystallization enthalpy. Probably the existence of microscopic inhomogeneities also plays a crucial role in the crystallization kinetics of other amorphous materials and glasses.

Deposition of Nanostructured Silicon Thin Films by Means of the Selective Contribution of Particles in Pecvd

PECVD processes are the most common way of growing amorphous and microcrystalline silicon thin films. These low pressure plasmas are known to generate large amounts of particles in the gas phase which may be a source of contamination in the production of silicon based devices. In this report, however, we show that these particles can be incorporated profitably into a growing film, provided that their size is controlled. The Modulation of the RF power is a direct method of controlling particle size. Plasma characteristics determine the dynamics of particle formation, whereas the duration of the plasma-on period controls the particle's size and atomic structure. The size and atomic structure of particles from two different periods of the same discharge were investigated. Their main characteristics, monodisperse size distribution and ordered atomic structure, are discussed in the context of the latest findings on particle nucleation and coagulation.

A semi-phenomenological model was used to show that, during the first milliseconds of the discharge, particles of 1–2 nm that are electrically neutral may leave the plasma and contribute to the growth of the film. Although these particles could not be observed on the TEM grid, their contribution to film growth might be relevant.

Restricted epitaxial growth of crystallites in hydrogenated nanocrystalline silicon during thermal crystallization experiments

Thermal crystallization experiments have been carried out on nanocrystalline silicon films. From the thermal activation of the process, it is concluded that the amorphous phase crystallizes by solid phase epitaxy around the preexisting crystallites. However, and in contrast with the usual epitaxial crystallization of wafers partially amorphized by ion implantation or ball-milled powders, the epitaxial growth is inhibited for most of the amorphous-crystalline interface. Our analysis indicates that a small fraction of the interface contributes to the epitaxial growth. Although the influence of oxidation and of Si-H groups located at the interface cannot be completely excluded, this behavior is explained in terms of a high density of microvoids located at the a-c interface. This result has implications for the models of electrical conduction of nc-Si:H.

[Genetic and environmental factors that may influence in the senile form of Alzheimer's disease: nested case control studies]

INTRODUCTION

We identify the genetic and environmental factors associated to Alzheimer's disease (AD) in a population aged 80 years or greater.

POPULATION STUDIED

subjects who participated in the COGMANLLEU study on prevalence of cognitive deterioration in Manlleu (Osona, Central Catalonia).

DESIGN

nested case control studies. The subjects who were diagnosed of AD (cases) in phases 2 of said study were paired 1:1 by age and gender with control subjects who were selected from among those who had no suspicion of cognitive deterioration and who had been examined in phase 1 of the study. The participating subjects (cases and controls) and their family or caregivers were interviewed. This included psychometric tests, physical examination, biological measurements, cranial computed tomography scan and determination of ApoE genotype.

RESULTS

Age is the principal factor associated to AD: risk of getting the disease is six time greater among those over 85 years (odds ratio [OR]: 6.54; 95% confidence interval [CI]: 2.05-20.81; p<0.05). Other factors associated of AD were female gender (OR: 3.17; 95 % CI: 0.80-12.50) and having been exposed to general anesthesia (OR: 3.22; 95 % CI: 1.03-10.09; p < 0.05). Arterial hypertension (AHT) presented a negative association (OR: 0.37; 95% CI: 0.10-1.31; p<0.05). An association was also observed between AD and the presence of ApoE4 allele so that the likelihood of ApoE4 in subjects with AD was three times greater than in the control group (OR: 3.44; 95% CI: 0.67-17.62).

CONCLUSIONS

The results agree with the hypothesis that senile AD is a complex, multifactorial disease in which different genetic and environmental factors play a part, among which having received general anesthesia has a role that can be considered in future research.

[Prevalence of cognitive deterioration in people over 80-years-old: COGMANLLEU study]

INTRODUCTION

We want to detect the prevalence of cognitive prevalence deterioration in the elderly population of 80-years-old or older, their grade of deterioration and the causal pathogenic entity.

DESIGN

a cross-sectional population study, including a first phase of screening and a second one of diagnosis confirmation.

STUDY SUBJECTS

a total of 877 elderly people of 80-years-old or older belonging to the basic health care area of Manlleu (Osona, Catalonia midlands). In the first phase, relatives and/or caregivers were interviewed, and the participating subjects underwent a set of tests. Those who obtained 24 points or less on the Mini-Mental State Examination (MMSE) and/or an equal Global Deterioration Scale (GDS) or over 3 were admitted to the second phase. During the second phase, a general and a neurological examination were performed, along with blood tests, cranial computed tomography scan and a neuropsychological study. DSM-IV criteria were used for dementia diagnosis, NINCDS-ADRA criteria for Alzheimer's disease (AD) and NINCS-AIREN for vascular dementia.

RESULTS

Half of the people over 80-years-old had cognitive deterioration. One-fourth had dementia. A total of 70.3% of these dementias corresponded to AD (47.2% AD without vascular lesions and 23.1% AD with vascular lesions) and 12% corresponded to vascular dementia. The percentage of other degenerative dementias was 17.6%. Age and gender were observed to be associated to dementia.

CONCLUSIONS

The prevalence of dementia in the COGMANLLEU study is similar to other European studies. AE is the most frequent dementia.

Community outbreak of Legionnaires’ disease in Vic-Gurb, Spain in October and November 2005

This paper reports the investigation of a community-acquired outbreak of Legionnaires'; disease in the municipalities of Vic and Gurb (Central Region of Catalonia, Spain). There were 55 cases reported in October and November 2005. An epidemiological and environmental investigation was undertaken. Thirty-five case patients (64%) lived in Vic or Gurb, while 36% had visited or worked in Vic or Gurb during the 10 days before onset of symptoms, but no commonly frequented building could be identified. Water probes for culture were obtained from 30 cooling towers. In five cooling towers of two industrial settings in Gurb (plants A and B), Legionella pneumophila (Lp) serogroup 1 was present. Two Lp-1 strains were recovered from cooling towers in plants A and B. The Lp-1 strain from plant A showed a PGFE profile identical with those obtained from three patients. The exposure to Legionella pneumophila apparently occurred in a large area, since 43 of the 55 cases lived, visited or worked within a distance of 1,800 m from plant A, and six cases in a distance between 2,500 and 3,400 m. The inspections of cooling towers in plant A revealed inadequate disinfectant doses of biocide, non-existent maintenance records on weekends and wrong sample points for routine microbial check-ups. Weather conditions in October 2005 template temperature and high humidity (wind conditions are unappreciable) could have been favourable factors in this outbreak together with the flat terrain of Gurb and Vic area, explaining the extensive horizontal airborne dissemination of contaminated aerosols. The outbreak could have been prevented by proper and correct maintenance of the cooling tower at plant A.

Community outbreak of Legionnaires disease in Vic-Gurb, Spain in October and November 2005

This paper reports the investigation of a community-acquired outbreak of Legionnaires' disease in the municipalities of Vic and Gurb (Central Region of Catalonia, Spain). There were 55 cases reported in October and November 2005. An epidemiological and environmental investigation was undertaken. Thirty-five case patients (64%) lived in Vic or Gurb, while 36% had visited or worked in Vic or Gurb during the 10 days before onset of symptoms, but no commonly frequented building could be identified. Water probes for culture were obtained from 30 cooling towers. In five cooling towers of two industrial settings in Gurb (plants A and B), Legionella pneumophila (Lp) serogroup 1 was present. Two Lp-1 strains were recovered from cooling towers in plants A and B. The Lp-1 strain from plant A showed a PGFE profile identical with those obtained from three patients. The exposure to Legionella pneumophila apparently occurred in a large area, since 43 of the 55 cases lived, visited or worked within a distance of 1,800 m from plant A, and six cases in a distance between 2,500 and 3,400 m. The inspections of cooling towers in plant A revealed inadequate disinfectant doses of biocide, non-existent maintenance records on weekends and wrong sample points for routine microbial check-ups. Weather conditions in October 2005 template temperature and high humidity (wind conditions are unappreciable) could have been favourable factors in this outbreak together with the flat terrain of Gurb and Vic area, explaining the extensive horizontal airborne dissemination of contaminated aerosols. The outbreak could have been prevented by proper and correct maintenance of the cooling tower at plant A.

[Smoking among adolescents: population study on parental and school influences]

OBJECTIVE

Smoking represents a public health problem, one which begins during adolescence. The main objective of this study was to analyze the association between smoking and parental and school factors.

SUBJECTS AND METHODS

The study sample consisted of the students from the 20 secondary schools in the region of Osona, Barcelona, Spain. A self-report questionnaire was used to obtain information on the following variables: smoking habit, age of initiation, frequency, type of school (state school or private-subsidized), sex, age, persons living in the home, town, whether the student had lunch at school, whether the student often had lunch or dinner alone at home.

RESULTS

A total of 2280 students participated in the study (91%). Mean age was 15.5 years. Of the participants, 20% said they were smokers; 5%, ex-smokers; 34% had tried smoking at least once, and 41% had never smoked. Factors significantly associated with smoking in the multivariate analysis were age, rural town, state school, single parent family, eating alone, and not lunching at school.

CONCLUSIONS

Smoking prevalence is high among adolescents in our society and there is no gender difference. Our results show that family structure and dynamics can influence smoking in adolescents. Smoking is less prevalent among adolescents who have lunch at school.

Local thermodynamic derivation of Young's equation

A derivation of Young's equation based on the energy balance near the contact line is presented. Our proposal is rigorous and avoids the errors identified in the usual local derivation. It is valid under very general conditions (for any geometry, in a gravitational field and for compressive fluids). Deviations of the contact angle from Young's equation are discussed in several cases: surfaces of high curvature and line tension. Finally, the relationship between surface tensions and surface energies comes as an additional, natural result. Our derivation also provides a new physical insight into the equilibrium of forces acting near the contact line. Its local character makes the recourse to integral analysis unnecessary, which results in a great simplification when compared to other general treatments.

Equilibrium of drops on inclined hydrophilic surfaces

Why does not gravity make drops slip down the inclined surfaces, e.g., plant leaves? The current explanation is based on the existence of surface inhomogeneities, which cause a sustaining force that pins the contact line. Following this theory, the drop remains in equilibrium until a critical value of the sustaining force is reached. We propose an alternative analysis, from the point of view of energy balance, for the particular case in which the drop leaves a liquid film behind. The critical angle of the inclined surface at which the drop slips down is predicted. This result does not depend explicitly on surface inhomogeneities, but only on the drop size and surface tensions. There is good agreement with experiments for contact angles below 90 degrees where the formation of the film is expected, whereas for greater contact angles great discrepancies arise.

[Cancer mortality in the counties of Catalonia (1983-1989)]

OBJECTIVES

To compare mortality among counties (comarques) in Catalonia, Spain for the most frequent malignant tumors.

METHODS

Overall mortality data and for five specific tumor sites were analyzed for a five-year period (1983-1989). Crude and site-specific mortality rates were computed. The comparison between counties was adjusted for the 1986 population of Catalonia using the direct method. Comparative mortality ratios (CMR) were obtained for each county with respect to Catalonia.

RESULTS

Overall cancer mortality was higher in the Barcelonès for men and in Osona form women. The CMR for men in the Barcelonès was the highest for cancer of the trachea, bronchi and lungs; the CMR in Solsonès was the highest for stomach cancer, while in Cerdanya it was the highest for colorectal cancer. Among women, the highest CMR for cancer of the trachea, bronchi and lungs was in Montsià, whereas for breast cancer it was Baix Empordà, and Alt Urgell for stomach cancer.

CONCLUSIONS

Comparative analyses of cancer mortality by county in Catalonia and sex underscores differences in its distribution, allowing the orientation of cancer control policies and research to be developed in each geographical area.

[Impact of consensus conferences of hypercholesterolemia and hypertension in Spain]

BACKGROUND

In May 1989 and June 1990, consensus conferences of treatment of hypertension and hypercholesterolemia respectively were held in Spain, at the General Division of Health Planning from the Ministry of Health. The objective of this article is to assess the effect of such conferences of physicians' knowledge, attitudes and practices.

SUBJECTS AND METHODS

Cross-sectional telephone survey was carried out in physicians of general medicine, family practice, internal medicine and cardiology specialties. 807 physicians were selected, 347 family physicians, 177 general practitioners, 156 cardiologists and 128 internists. A questionnaire of 30 items was designed to obtain information about demographic and professional characteristics, knowledge of the consensus conferences and attitudes related to a case of an otherwise healthy asymptomatic 48-years-old man.

RESULTS

The response rate was 57% (463 physicians), and 60% of physicians had knowledge about the conferences, being general practitioners the ones who had less knowledge of the conferences. The items about recommendations of diet and pharmacological treatment were property answered (about 50% of the physicians answered correctly). The mean of serum cholesterol when diet and drugs are recommended was 232 mg/dl (SD 23) (6.01 mmol/l) and 260 mg/dl (SD 25) (6.7 mmol/l) respectively. The first-choice cholesterol lowering drugs were statines. A patient was considered as hypertensive it the mean of systolic blood pressure was 149 mmHg (9.4) and the mean for diastolic blood pressure was 92 mmHg (3.8). The mean of diastolic blood pressure considered for drug treatment was 96.7 mmHg (SD 4.6). The first-choice antihypertensive drugs were angiotensin conversive enzyme inhibitors.

CONCLUSIONS

Diffusion of the conferences has been unequal, being general practitioners less knowledgeable about the content of the conferences. Although physicians know reasonably well the recommendations about diet and drug treatments, the attitude in practice is more aggressive than recommended. Globally, the knowledge of the contents of the conferences was acceptable, although there were differences between specialties; however the effect on clinical practice is still low.

[The effectiveness of breast cancer screening in our country]

The aim of this paper is to review the current state of breast cancer screening in our country, as well as to discuss the most appropriate approaches for its development. Firstly, the impact of breast cancer in Spain is presented, as well as the current evidence about the efficacy of the screening. The major programs and initiatives addressed to promote screening are described. Finally, a few recommendations are given in order to achieve that breast cancer screening be, not only efficacious, but also effective. It is concluded that it is necessary that health and professional authorities coordinate and monitor breast cancer screening programs.